The present invention relates to a process for the measurement of parameters in reactors having moving stirrers which contain probes in the reactor interior, wherein at least two probes connected to a sensor signal amplifier by connecting cables located in the moving stirrers are installed on the surface of the moving stirrers, and the measurement data obtained by the probes are passed via the connecting cables to a sensor signal amplifier and from thence are passed on to an electronic evaluation unit by non-contact, inductive signal transmission by means of a contactless sensor tap.
The present invention furthermore relates to a device for the measurement of parameters in reactors having moving stirrers.
For reaction control and monitoring, temperature probes and occasionally also pressure probes are frequently installed at a wide variety of points in chemical reactors. This is particularly necessary in polymerization reactors, since the heat of reaction generated therein by the polymerization must be rapidly dissipated again, making it necessary to determine the change in pressure and temperature in the polymerization reactor as accurately as possible. The temperature probes used are usually thermocouples fed into the interior of the reactor through the reactor wall or via a dip tube.
In numerous polymerization reactors, use is frequently made of moving stirrers in the reactor interior for keeping the reaction bed, which is frequently pulverulent, in motion. For such purposes, vertical, self-supporting helical stirrers are particularly suitable; these are disclosed, inter alia, in EP-B 000 512, EP-B 031 417 and EP-B 038 478. During operation, the self-supporting helical stirrers convey the powder bed present in the reactors toward the top.
In reactors having stirrers in their interior, the problem frequently arises that it has hitherto not been possible to install pressure or temperature probes in the actual working area of the stirrer, i.e. at the point in the interior where the greatest mixing of the reactor contents takes place and the main energy input by the stirrer occurs, since the movement of the stirrer prevents this. For this reason, the pressure and temperature probes have hitherto either only been attached to the reactor wall or only installed in the interior of the stirrer by introduction of a dip tube. Installation of, for example, a plurality of probes at different points of the reactor allows temperature or pressure distributions in the reactor interior to be determined, but this does not usually allow reliable information to be obtained on the parameter distribution in the actual working area of the stirrer since no corresponding probes are present there.
Neither has it hitherto been possible in the reactors described in EP-B 000 512, EP-B 031 417 and EP-B 038 478 to determine pressure or temperature distributions in the actual working area of the self-supporting helical stirrer, since conventional probes cannot be installed there owing to the specific geometry of the self-supporting helical stirrer. In such reactors, the pressure or temperature measurement is effected by conventional probes installed on the reactor wall or else in the free interior of the helical stirrer within dip tubes formed therein. However, the resultant pressure or temperature distributions do not give a reliable picture of the pressure or temperature conditions prevailing in the actual working area of the self-supporting helical stirrer, i.e. between the wall region of the reactor on the one hand and the helical stirrer's free interior provided with dip tubes on the other hand.